Life-course weight characteristics and the risk of gestational diabetes

Abstract

Aims/hypothesis: We prospectively determined the risk of gestational diabetes mellitus in association with life-course weight characteristics and adult abdominal adiposity.

Methods: We investigated the joint and independent impact of birthweight, childhood size by somatotypes, adolescent and adult BMI, and abdominal adiposity on gestational diabetes mellitus risk among the 21,647 women in the Nurses' Health Study II who reported a singleton pregnancy between 1989 and 2001. A total of 1,386 incident cases of gestational diabetes mellitus were reported. Relative risk was estimated by pooled logistic regression adjusting for age, prematurity, race, smoking status, parental history of diabetes, age of first birth, parity and physical activity.

Results: Birthweight was inversely associated with gestational diabetes mellitus risk (p = 0.02 for trend). Childhood somatotypes at ages 5 and 10 years were not associated with risk. U-shaped associations were found for BMI at age 18 years and somatotype at age 20 years. Weight gain between adolescence and adulthood, pre-gravid BMI and abdominal adiposity were positively associated with risk (p < 0.01 for all trends). Multivariate adjusted RRs for gestational diabetes from lowest to highest quintile of WHR were 1.00, 1.50, 1.51, 2.03, 2.12 (p = 0.0003 for trend). Lower birthweight (<7 lb) without adulthood overweight (BMI > 25 kg/m(2)) was associated with a 20% increased risk (95% CI 1.02-1.41). However, adulthood overweight alone was related to a 2.36 times greater risk (95% CI 2.12-3.77).

Conclusions/interpretation: Although lower birthweight is an independent risk factor for gestational diabetes mellitus, weight gain since early adulthood, and overall and central obesity in adulthood were more strongly associated with elevated risk of the condition independently of other known risk factors.

Fig. 1

Flow-chart of primary exposure data collected at baseline and follow-up in the Nurses’ Health Study II. Prospective analysis of central adiposity measures included only women with a pregnancy after the collection of this data in 1993 to end of follow-up in 2001 (n=4,981). Adult BMI, age at first birth, parity, smoking, and physical activity were updated in biennial questions.

Fig. 2

Relative risks (95%CI) of GDM by quintiles of waist (A), waist-to-hip ratio (B), and waist-to-height ratio (C) (n=4,981). The upper line (--◆--) shows multivariate adjusted risks, which were adjusted for age, race, smoking, maternal and paternal history of diabetes, age of first birth, parity, physical activity. The lower line (⋯■⋯) shows risks with the addition of continuous BMI to the model above. All trends were significant (p<0.005).

Fig. 2

Relative risks (95%CI) of GDM by quintiles of waist (A), waist-to-hip ratio (B), and waist-to-height ratio (C) (n=4,981). The upper line (--◆--) shows multivariate adjusted risks, which were adjusted for age, race, smoking, maternal and paternal history of diabetes, age of first birth, parity, physical activity. The lower line (⋯■⋯) shows risks with the addition of continuous BMI to the model above. All trends were significant (p<0.005).

Fig. 3

Women were stratified by low birth weight (< 7.0 lbs), adolescent overweight (BMI>25 at age 18 years), and adult overweight (BMI>25 at baseline). The reference category for the associations consisted of women who did not report any of these conditions. The adjusted relative risks (95%CI) of GDM among women reporting each of these exposures independently and in combination are shown.